Lester is due to start for the Chicago Cubs against San Diego on Sunday and would be unavailable for Tuesday's All-Star Game at Nationals Park in Washington.

After some early struggles, Zack Greinke has gone 6-3 with a 2.88 ERA since May 9. Andy Cross/The Denver Post via Getty Images

This is the fifth All-Star selection for Greinke, who has a 9-5 record with a 3.39 ERA, 117 strikeouts and 23 walks in 114 innings. Since May 9, he has gone 6-3 with a 2.88 ERA in 13 starts.

The 2009 Cy Young winner struggled in spring training, with a fastball that was only in the mid-80s, and at one point said he wondered if he still had what it took to pitch.

For that reason, Greinke, 34, said this All-Star nod is his most meaningful.

"You guys that saw me pitch in spring training -- I didn't know if I was going to be able to get any outs this year," he said Thursday. "To end up doing as good as it's been so far, it's pretty exciting."